Bitbucket Pipelines lets you select from any Docker image on the Docker Hub. The set of official images, maintained by Docker, is already too long to list here but includes the popular languages listed above, as well as other languages, frameworks, and platforms. Have a look for yourself: https://hub.docker.com/explore/

The only requirement specific to Bitbucket Pipelines is that it must contain Bash (all Ubuntu-based images do).

In this way, Docker is how you configure Bitbucket Pipelines with the tools, libraries, and other dependencies you might need during build. Hence, the "and more" is really only limited by what you can put into a Docker container and post to Docker Hub (or even a private registry, if necessary).

Is it possible to access the build artifacts from Pipelines? Part of my workflow for merging pull requests is testing the build (unfortunately it's still manual) itself, not just checking to see if it builds.

Sorry for the long delay... Short answer, no. The whole container is destroyed when the build is completed. Build artifacts must be put somewhere as part of your pipeline, if you want them to survive. There are examples for S3, Artifactory, and Nexus.